Method and apparatus for making packing rings



July 25, 1933. w. coRD's 1,919,584

METHOD AND APPARATUS FOR MAKING PACKING RINGS Filed Feb. 4, 1931 I gwuentov 43 William Cords Patented July 25, 1933 PATENT OFFICE WILLIAM CORDS, OF SAN DIEGO, CALIFORNIA METHOD AND APPARATUS FOR MAKING PACKING RINGS Application filed February 4, 1931.

This invention relates to methods and apparatus for conveniently making packing rings by hand from straight bands of metal.

More particularly, the invention relates 5 to a method of making sealing rings, whereby the rings are given characteristics that peculiarly adapt them for the purpose for which they are manufactured, and to an extremely simple portable apparatus for bending rings in accordance with said method into split annular form of any desired diameter within reasonable limits.

Another object of the invention is to provide a novel machine for bending piston rings, having a width many times the thickness of the rings, for compelling the ring to assume a slightly dished form during the bending operation, by putting the metal adjacent the outside thereof under tension so that upon further contraction of the ring, in' placing it in a cylinder, the dishing thereof is increased.

A further object of the invention is to provide a method of bending steel or simi- 5 lar packing rings having a width many times the thickness of the ring on lines transverse to the width of the rings, in such a Way as to permit the ring to assume a slightly dished form during the "bending operation, while at .the same time limiting the extent to which the ring is permitted to assume such form during said operation.

Another object of the invention is to pro packing ring formed by the machine of the present invention, the ring being shown in full lines inits manufactured form, and in dotted lines in the form it assumes when put into use.

Figure 2 is a sectional view taken on the plane indicated bythe line 22 in Figure 1, looking in the direction of the arrows, the

Serial No. 513,440.

dotted lines showing the ring contracted as when put into use.

Figure 3 is a plan view of a preferred form t of portable apparatus or tool designed for the cold bending of the rings of the present invention by hand.

Figure 4 is a view of said apparatus as seen from the bottom thereof. 7

Figure 5 is a side elevational view, looking toward the right in Figure 3.

Figure 6 is an end elevational view looking toward the bottom of Figure 3.

Figure 7 is a sectional view taken on the plane indicated by the line 77 in Figure 4.

Figure 8 is a fragmental sectional view of a modified form of bending die on a. slightly enlarged scale.

Like reference characters indicate like parts throughout the several figures.

The purpose of the present invention is to form rings of thin resilient metal having a width many times the thickness of the metal utilized in forming the ring. Preferably, the rings are constructed from oil-tempered ribbon steel bands having a width of about of an inch and a thickness of .020 inches. The rings are -constructed by bending them into approximately circular form from straight strips of metal of the character just stated cut to the necessary length.

The ring is bent, while cold, on lines transverse to the width of the band of metal from which the ring is formed, and use is made of the fact that the portions of the metal to the outside of the neutral axis are stretched or put under tension during the bending operation, while the portions of the metal to the inside of the neutral axis are compressed, to give to'the completed ring the characteristic of'conforming readily to the contour of the walls of the cylinder in which it is caused to operate. It will be found that if a thin band of metal having a width many times the thickness of the band is bent on lines normal to the width of the band, that it will have a tendency to assume a dished form during the bending operation. By this invention it is proposed to permit the rings to assume such form to a limited or slight degree during the bending operation. This tendency arises by virtue of the stretching of the portions of the metal beyond the neutral axis and the compression of the portions of the metal to the inside of the neutral axls just referred to. A strip may be bent in this way to form a piston ring that is capable of being readily contracted in positionmg it in the cylinder, in which it is to operate to a very substantial degree without setting up in the rings very substantial forces tending to expand it when in operation, which forces would manifest themselves by an excessive wear of the cylinder walls. On the other hand, due to the fact that the rings of the present invention may be contracted substantially in placing them in the cylinder, said rings have a distinct tendency to follow and conform accurately to the walls of the cylinder. Nevertheless the ring is highly flexible, and does not apply a great degree of pressure against the walls of the cylinder with the result that wear is minimized, though an effective seal is provided.

Referring to the drawing, the numeral 10, Figure 1, designates an improved piston ring constructed in accordance with this invention. The ends 11 and 12 of the. rings are relatively widely spaced apart as shown in full lines in said figure, this representing the normal condition of the ring prior to its application to the cylinder. As illustrated in alarge stock of rings of various sizes be the drawing, the ring has a width many times the thickness thereof. As a preferred example, the width of the rings may be of an inch, while the thickness thereof is approximately .020 as above stated, though other dimensions may be selected. The ring is bent from a straight strip or band of metal in a manner hereinafter described, the bending taking place on lines normal to the width of th strip. When the strip is bent in this way, the portions of the metal adjacent the neutral axis 13, which is approximately at the center of the strip, are neither elongated nor compressed. However, the portions of the metal on the outside of said neutral axis designated by the numeral 14, Figure 2, are stretched during the bending operation, while the portions 15 of the metal disposed inwardly of the neutral axis 13 are compressed. This results in the strip assuming a slightly dished form, if it is permitted to do so during the bending operation, and preferably the piston rings of this invention are bent in such manner that the ring is permitted to become slightly dished during the bending operation. The dishing, however, is exaggerated in Figure 2 of the drawing in the interest of clearness.

Preferably, the ends 11 and 12 are spaced apart sufiiciently so that the rings may be contracted to a size 1 3' of the original diam eter thereof, the ends 11 and 12 being brought into relatively close proximity, as illustrated in dotted lines in Figure l of the drawing. When the ring is contracted in this manner, to cause it to fit within the cylinder in which it is to operate, it will be understood that the dishing of the ring is increased by .the operation of contraction thereof, as illustrated in dotted lines in Figure 2, though the dishing of the rings is exaggerated in this figure.

The rings thus formed have-a high degree of resilience and an ability to confrom to the walls of the cylinder, providing a tight seal though the rings bear relatively lightly upon the walls of the cylinder. The effectiveness of the ring as a seal is materially increased, by virtue of the fact that the dish ing of the ring in contracting it to fit in the cylinder and in the process of its formation, provides a line contact between the ring and the walls of the cylinder.

Preferably, the rings of the present invention are bent into the desired form by means of an apparatus disclosed in Figures 6 to 10 of the drawing. The apparatus about to be described may be readily operated by hand. In view of the simplicity of the apparatus, it is proposed to provide an apparatus, by which the rings may be formed, to users and distributors of piston rings, permitting the users or distributors to bend the rings to the desired diameter in accordance with the demand. It is accordingly unnecessary that maintained by such user or distributor. The apparatus about to be described represents a preferred arrangement for bending the rings into the form of a split annulus though, as will be obvious, other equivalent arrangements can readily be provided.

Referring to the drawing, indicates the base of the apparatus, which may be in the form of a plate-like member having a widened end 31 and a narrower portion 32. The bending elements are disposed adjacent the wider portion 31 while the narrow portion is utilized to conveniently attach the device to a work bench or similar support adapted to sustain it. One side of the plate is provided with a tubular hub 33, that is preferably formed integral witha reinforcing or strengthening 'rib 34 extending lengthwise of the plate.

The other side of the plate is provided with a jaw 35 extending away from the base plate in spaced relation to a lug 36 through which a clamping screw 37 is threaded. Said screw is provided with a thumb piece 38 permitting manipulation thereof in clamping the device to a workbench,- a portion of said bench being disposed between the jaw 35 and the adjustable jaw provided by the end of the screw 37, whereby the apparatus may be convenientroller bending die and feed roller 43 provided with teeth 44. A groove 45 is formed in the roller 43 preferably midway between the edges of the teeth 44 and to a depth slightly exceeding the depth of the teeth, said groove being provided to receive the band to be bent in the manner hereinafter described.

J ournalled on the end of shaft 44, remote from the handle 41, is an arm 46, which is retained on said shaft by means of a bolt 47 having a threaded shank 48 engaging in a threaded bore 49 in the shaft 39. A shaft 58, provided with reduced threaded extensions 49 and 50, is rigidly secured to the arm 46 by passing the'reduced extension 49' through an opening in said arm. and clamping the arm 46 in contact with the shoulder formed by shaft 58 by means of a nut 51 threaded on the reduced extension 49'. The reduced threaded extension 50- is disposed in a slot 52 that is curved with respect to the center of the shaft 49 and arrangedin the wide portion 31 of the base plate 30. The position of the shaft 58 along the curved slot 52 may be fixed at any point thereof by clamping a thumbnut 53, that is threaded on the reduced extension 50 and that engages the side of the plate 30 opposite the shoulder. provided by the reduced extension 50, so that when the thumbnut 53 is adjusted, the shaft is immovably positioned with respect to the plate 30 at any point along the curved slot 52.

A combined feed roller and bending die 55 is journaled on the shaft 58, said roller being provided with gear teeth 56 meshing with the teeth 44 of the die 43. The combined feed roller and bending die 55 is provided with a circumferentiallv extending groove 57 arranged so as to be disposed exactly opposite the groove 45 in the roller die 43, providing with the groove 45 a pass between the rolls 43 and 55 for the band of material to be bent into the form of the split annulus. A shaft 60, provided with a head 61, and a reduced threaded extension 62, serves as a means for rotatively supporting a third roller bending die 63, having teeth'64 that likewise mesh with the teeth 44 of the roller bending die 43 above described. The die 63 is provided with a groove 65 that matches the groove 57 in the die 55 and the groove 45 in the die 43. The roller die 63 is secured to the base 30 by entering the reduced threaded ex ers.

said slot and fixed in any position by then adj usting said nut.

In the, operation of the apparatus just described, the band of straight metal to be bent into the form of a split annulus, is entered into the pass between the dies 43 and 63,

through the matching grooves 65 and 45 provided in said dies. Prior to the insertion of the strip between the dies 63 and 43, the die 63 is fixed in some position along the curved slot 52. The thumbnut 53 is released so that the arm 46 carrying the roller die 55 may be swung intothe position indicated by dotted lines in Figure 7, so that the pass is provided between the roller so that the matching grooves 57 and 43 in said rollers arebrought into position to receive the strip disposed in the matching grooves in the dies or rollers 43 and 63. By operating the handle 42 and rotating the die 43, the teeth 44, meshing with the teeth 64 and 56 of the dies 55 and 63, will cause simultaneous rotation of the three roller dies, which then function 'as feed rollers, as well as bending dies, and advance the strip throu h the matching grooves in said rollfter the bending of the strip has been initiated in this manner, the arm 47 is operated to cause the ro1ler'55 to move along the curved slot 52 in accordance with the desired diameter of the split annulus being formed.

The portion 31 of the base 30 may be provided with suitable indicia indicating diameters of the split rings to be formed to enable the operator to readily determine the position of the roller 55 to fit any particular diameter, though it should be understood that accuracy in bending is not essential, inasmuch as the rings have a high degree of flexibility and readily adapt themselves to the walls of the cylinder to which they may be applied. It is preferred, as above stated, to bend the split annular rmgs into a diameter approximately greater than the diameter of the cylinder in which the rings are to be used, though, as just stated, accuracy is not required. When the operator has moved the hand 47 to the desired position and the thumbnut 53 is adjusted, fixing the position of the die 55 on the base plate 30, funther rotation of the dies and feed rollers by means of the handle in the manner just stated, results in a bending of the strip, or band which is cut to a proper length, intothe form of a split annulus. The strip may be cut either before or after the bending operation. If desired, suflicient material-in strip form may be run through the rolls to form a plurality of endless convolutions which do not reenter the pass, but which, due to the flexibility of the material, will distend laterally and accur'nulate in a continuous spiral at the left side of the machine (Figure 5), after which the a the material of which the rings are to be formed, so that there is a slight play between the sides of said matching grooves and the strip disposed therein. By virtue of this arrangement, the rings are permitted to assume a slightly dished form as they are bent into the form of an annulus. As above stated, a fiat band has a natural tendency to assume such form when the outward portions beyond the neutral axis thereof are stretched when bending, and the portions to the inside of the neutral axis are compressed. The rings are accordingly permitted to assume a slightly dished form, the extent of which is determined by the width of the grooves in the bending dies when the straight strips are bent into the required form. Rings that are bent in this manner and provided with a slight dishing in the manner just stated, have a higher degree of flexibility and are capable of being contracted to the size of the cylinder in which they are placed, the dishing being increased by said contraction.

To provide for the adjustability of the grooves 45,55 and in bending dies 43, 55 and 63, the die construction shown in Figure 11 may be utilized, in which the die member 71 has formed integrally therewith annular bending section 7 2 provided with driving teeth 73, and is threaded at 7 4 to receive the tapped collar 7 5. Collar 75 is provided with teeth 76 similar in pitch and shape to, and adapted to align with teeth 7 3. A looking ring 77 threaded on section 74. is provided to lock member 75 in adjusted position to form bending groove 78.

When it is desired to adjust the width of the bending groove 78, looking ring 77 may be loosened and collar 75 adjusted along threaded section 7 4 to give the desired width of groove 78, with teeth 76 and 73 in alignment. Locking ring 77 is then tightened to lock collar 75 in adjusted position. By substitution of this adjustable die construction for bending dies 43, 55 and 63, in a manner that Will be obvious to those skilled in the art,'pist0n rings with any desired diameter and degree of dish may be conveniently and rapidly turned out.

The invention may be embodied in other specific forms without departing from the to rotate said rollers to advance the blank and to cause it to be bent into annular form by said roller die during its advancement.

2. An apparatus for bending a blank having a width greatly in excess of the thickness of the blank into the form of a split annulus, comprising a pair of grooved feed rollers, a grooved roller die adjustably mounted with respect to the pass between said feed rollers, the grooves in said feed rollers and die being of a width greater than the thickness of said blank so that the blank is free to assume a slightly dished form during the bending thereof into the form of a split annulus.

3. An apparatus for bending a substantially flat metal blank, having a width greatly in excess of its thickness, edgewise into the form of an annular ring, said apparatus comprising a frame, a. pair of rollers supported by said frame and having matched grooves cooperating to form a pass for receiving the blank with the lateral bounding planes of said pass normal to the roller axes and forming a space of a width greater than the thickness of the entering flat blank, bending means carried in predetermined position relative to' said frame to impart a given final shape to the ring, and means for driving one of said rollers.

4. An apparatus for bending a strip of relatively thin metal into the form of a light resilient piston ring, said apparatus comprising a set of cooperating feeding and shaping rollers, and means provided by said rollers for imparting a uniformly dished shape to the ring whereby the latter is given an overall thickness which is greater than the thickness of the metal which forms the said rlng.

5. In an apparatus for bending a strip of thin metal edgewise into the form of an annular ring, means forming a pass of greater width than the thickness of the metal for receiving the strip during its passage through upon a stationary support, a set of short feedmg and shaping rollers coupled together for simultaneous rotation, one of said rollers being ournaled on said frame plate and provided at one end with a manipulating crank, an arm pivoted upon the opposite end of said one roller, another of said rollers being carried by said arm, said rollers cooperating to form a pass for curving the blank edgewise with respect to the roller axes, and means for adjustably clamping said arm against pivotal movement relative ,to the frame.

7 A simple manually operable device for bending a li ht blank into curved form, said device inclu ing a frame comprising a light plate, a set of feeding and shaping rollers coupled together forsimultaneous rotation adjacent one side of said late and for cooperation to form a pass or the blank, pins carried by said plate for mounting several of said rollers, an arm journaled on one of said pins on that side of the rollers opposite said plate, an additional pin carried by said arm to support another of said rollers, means carried by said additional pin for clamping the arm relative to the plate, and means provided on one of the pins associated with the arm for preventing lateral separation of the arm and plate.

8. In subcombination, in an apparatus for reshaping an elongated piece of material, a rotatable member provided with an external set of teeth, and means disposed adjacent said teeth on said member for cooperation with one side of the set of teeth to form a pass for the piece of material, said means comprising a second set of teeth adjustable toward and from the first mentioned set to vary the size of said pass.

9. In subcombination, in an apparatus for reshaping an elongated piece of material, a rotatable member provided with an external set of teeth, and means disposed adjacent said teeth on said member for cooperation with one side of the set of teeth to form a pass for the piece of material, said rotatable member having an externally threaded lateral hub, and said means being mounted on said hub for movement toward and from said teeth and includin screw threads for positioning it on said hub.

10. The method of making a dished piston ring from a band of metal of a width greatly in excess of its thickness which consists in bending the band of metal into annular form on lines transverse to the width of said band in a manner permitting the resultant compression of the metal adjacent the inside of the ring and the resultant tension of the metal adjacent the outside of the ring to draw said band into a slightly dished form.

11. The method of making a dished piston ring from a band of flat metal of a width greatly in excess of its thickness, which consists in bending the band into annular form by application of pressure to the edge thereof to bend the band on lines normal to the width of the band while maintaining the other surfaces free of pressure so as to cause the band to assume a dished form as an incident to the bending operation.

12. The method of making a dished piston ring from a band of metal 0 a width greatly in excess of its thickness, which consists in bending the band into annular form by application of pressure to the edge thereof to bend the band on lines normal to the width of the band while maintaining the other surfaces free of pressure so as to causethe band to assume a dished form as an incident to the bending operation, and in limiting the extent of lateral deflection of the strip so as to determine the extent of dishing of the ring.

WILLIAM CORDS. 

